Quantification of Raman relaxation times in the Co4Rad3 tetramer

Determine the Raman spin-lattice relaxation time for the hypothetical tetramer Co4Rad3 constructed by linearly extending the Co2Rad dimer and assuming identical spin Hamiltonian parameters and spin–phonon coupling, since the authors could not numerically estimate these times due to their extreme magnitude.

Background

To study nuclearity effects, the authors extended the Co2Rad dimer to a trimer and tetramer while keeping the spin Hamiltonian parameters and spin–phonon coupling identical to those of the dimer. They found a dramatic slowdown of Raman relaxation with increasing nuclearity.

For the tetramer Co4Rad3, Raman relaxation was so slow that their numerical method could not resolve the timescale, leaving the quantitative value of the Raman relaxation time undetermined.

References

Interestingly, if a tetramer, Co4Rad3, is now considered, Raman relaxation times become so long that we cannot numerically estimate them, but Orbach relaxation remains virtually identical to Co3Rad2.

— The spin-phonon relaxation mechanism of single-molecule magnets in the presence of strong exchange coupling  (2412.04362 - Mondal et al., 2024) in Results – Relaxation in clusters of larger nuclearity (paragraph discussing the tetramer Co4Rad3)